¨Remember that even in mixed groups of elements, the trends in the periodic table still hold true. Atom size, ease of removing electrons, and ability to form bonds can be predicted as you move across and down the table.

¨The boiling points, melting points, and densities of the metalloids vary. The metalloids make good semiconductors. The metalloids are located along the diagonal line between the metals and nonmetals in the periodic table

¨Silicon and germanium are examples of metalloids.

¨Elements that have some properties of metals and some properties of nonmetals are called metalloids.

¨Hydrogen has a single positive charge, like the alkali metals, but at room temperature, it is a gas that doesn't act like a metal. Therefore, hydrogen usually is labeled as a nonmetal.

¨The lanthanides are silvery metals that tarnish easily. They are relatively soft metals, with high melting and boiling points

¨When you look at the periodic table, you'll see there is a block of two rows of elements below the main body of the chart. The top row has atomic numbers following lanthanum. These elements are called the lanthanides

¨The alkali metals are located in Group IA (first column) of the periodic table. Sodium and potassium are examples of these elements.

¨Most elements are metals. There are so many metals, they are divided into groups: alkali metals, alkaline earth metals, and transition metals. The transition metals can be divided into smaller groups, such as the lanthanides and actinides.

¨You see metals every day. Aluminum foil is a metal. Gold and silver are metals.

sets of groups. The group A elements are called the representative elements. The group B elements are the nonrepresentative elements.

elements that have the same outer electron arrangement.

Colums of elements help define element groups. Elements within a group share sevrrel common proporties.

The period number  of an element significs the highest element.  The number of elements in a pereodic table increases as you moove down the periodic table because there more  sub leveles per level as the energy level of the atom increases.

¨Atomic number increases as you move across a row or reired. Rows of elements are called periods.

Mendeeve crated the periodic table because the peridodic tablke helped predict the proporties

crated the periodic table because the peridodic tablke helped predict the proporties

 

¨You can tell the elements apart because they have different proporties. Dmitri mendeleev was the frirst scentist to create a periodic table of the elemnts similar to the ones we use today.

People have known about elements since ancient time. The elements couldn’t be change using any chemical method.